Studies on the volatile fatty acids of sheep blood with special reference to formic acid

Abstract

A method was developed for complete analysis of volatile fatty acids (VFA) present in 10-20 ml of blood. Formic acid was identified as a constituent of sheep blood and normally accounts for 10-30% of the molecules of VFA present. Chromatographic evidence was obtained indicating that formic acid was present in human blood and in the blood of goats, cattle, horses, rabbits, cats and dogs at concentrations similar to those seen in sheep blood. No evidence was obtained for uptake or production of appreciable amounts of formate by tissues of actively secreting mammary gland of the goat, or of the head of the sheep. Examination of the VFA found in the alimentary tract of the sheep suggested that the formate in the peripheral circulation was probably not derived from this source. Small amounts of VFA were shown in sheep urine (0.17-0.28 mM/l). Relative proportions of formate and acetate were similar to those seen in blood. Daily output of VFA in the urine was in the range 0.15-1.5 mM, which represents a negligible energy loss to the animal. Larger amounts of VFA were found in dog urine (0.40-1.09 mM/l), and the proportions of formate and acetate were similar to those observed in dog blood, approximately 1:1. Investigation of distribution of blood VFA''s between cells and plasma in sheep and cattle indicated that formate is considerably concentrated in the cells.